Rubber products



Patented Sept. 29, 1942 RUBBER raonnc'rs i Thomas Lewis Shepherd,Portslade, England, as-

signor' to The Clark Thread Company, Newark, N. J., a corporation or NewJersey No Drawing. Original application unitar 22,

1938, Serial N0. 186,467.

Divided and this air plication June 30, 1941, Serial No. 400,564. In

Great Britain August 4, 1935 .7 Claims.

This invention relates-to rubber products in thread, filament or tapeform, and is a division of my United States application Ser. No.186,467, filed January 22, 1938, the latter application in turn being acontinuation in part or division of my application Ser. No. 72,219,filed April 1, 1936.

Rubber may be manufactured in such form by' extruding latex with orwithout other ingredients such as vulcanisers, accelerators, reinforcingfillers, anti-oxidants and stabilisers.

In my U. S. Patent No. 2,203,701, granted June 11, 1940, I describeprocesses in which there is mixed with the latex or latex mixture forextrusion purposes various setting agents, such as glue, gelatine andsimilar proteins, casein albumen or the like, natural and syntheticresins and gums which are water or alkali soluble, cellulose etherswhich are water or alkali soluble, e. g. methyl cellulose andsubstances, inorganic or organic, which dissolve in water or dilutealkalies to given solutions which are miscible with latex. When thelatex mixture is extruded or otherwise formed into thread by coagulatingthe rubber, and dried, a set thread is produced, which may be woven orotherwise manipulated without the difficulties associated withextensible threads.

In U. S. Patents Nos. 2,182,996, 2,122,728, 2,122,- 727 and 2,131,981processes are described in which rubber thread is provided aftercoagulation with a soluble or insoluble coating such as glue, gelatine,suitable cellulose derivatives, starch, wax, resin or the like, varnish,such as gum dammar or copal, solutions of rubber or latex. By this meansthread with no, or only a limited stretch, is produced, which may beincorporated in fabrics without the dimculties associated with themanipulation of extensible threads, and this thread may be renderedextensible in the case of the soluble coatings by dissolving the latterout.

By the present invention I improve or modify the threads described inthe above-mentioned patents, and in this way produce a thread withimproved properties more particularly from the point of view, amongother things, of strength and of the property of being non-hygroscopic.

I have discovered that a thread which has been formed from latex and asetting agent may be greatly strengthened by providing it with acoating, and, at the same time, the coating is bett\er able to attachitself to the thread when this is formed of rubber with a setting agent.I may or may not dissolve out the coating and setting agent and in acase when I do not, but, on the contrary, render the coating, forinstance,

gelatine insoluble by means of formaldehyde, 55

alum, potassium dichromate or the like, a thread ing ofextensibility-reducing agent to the thread,

and hardening the coating. After forming a fabric from such thread theextensibility-reducing agent and the coating may be simultaneouslyremoved, by treating the fabric, for example boiling the same, in adye-containing solvent for the coating.

The rubber thread according to this invention may contain less than halfrubber and compounding materials for rubber, the remainder being settingagent and coating, for example per cent. or, at most, 45 per cent.rubber contents and compounding materials and per cent. or, at least, 55per cent. glue and gelatine.

In carrying the invention into efiect in one This mix is warmed slightlyand to it is addedwhilst stirring is effected50 per cent. glue solutionin such a quantity as will correspond with 15 parts of dry glue to ofdry rubber. Such a composition is extruded warm or even hot into acoagulation bath comprising a solution of the following formulamaintained at the desired tem- The coagulation bath solution need not ofnecessity be hot or warm but may also be cold and the extrusion orthread making point where the mix in thread form leaves the threadforming point is kept warm or hot or may be cold.

v A thread prepared by extrusion and subseqent coagulation from a mixsuch as that above specified, is dried or dried and vulcanised. Further,to obtain an improved thread it may after coagulation be run into a bathor through a bath of a liquid such as ethyl alcohol which will removethe majority of the water from the thread causing the precipitation ofthe glue. The thread after passing through or being left in the bath ofalcohol or similar liquid is then dried and, if desired, vulcanised. Thethread obtained using the second bath of alcohol is more limited instretch than that obtained using heat to remove the water. For thedrying of the thread after the treatment with alcohol a tunnel heated toa low temperature maybe employed or the thread may be passed from thealcohol bath through starch or chalk or any suitable powdering agent,collected and allowed to dry at room temperature.

The coating may then be applied in any suitable way as by painting,spraying or otherwise, or the thread may be passed through a bath of thedesired liquid so that it picks itup in transit.

The thread may also be treated by coating a vulcanised or u'nvulcanisedthread under a desired degree ofstretch for instance 20-25 per cent.with a suitable kind of soluble adhesive. Such an adhesive coating whichmay be a quick drying one may consist of glue, gelatine (equal parts byweight in water), a solution of a cellulose derivative, starch, moltenwax, resin or the like, or a suitable varnish such as gum dammar orcopal. It may be applied by coating, spraying or otherwise,before theprocess of weaving. The coating will be applied and allowed to dry tosuch a degree as will impart to the thread a rigid or semi-rigid set sothat the resulting thread will not possess the characteristic ofstretch, and is deprived of its elasticity or resilience as before.

As stated above, the adhesive used may be of such a character that itwill quickly dry, but if necessary the drying can be accelerated byartificial drying means of any kind.

The thread may be coated by suitable means (any known means) with acoating or skin of a gelatine solution, the strength of which may varyto a very great'extent, say from parts by weight of gelatine in 90 partsof fluid (water) up to 75 parts of gelatine by weight and 25 parts offluid (water) to whichmay be added according to requirements certainquantities of fiexlser, more especially glycerine, varying from 3 percent. (by weight) of the gelatine-water total up to 25 per. cent. (byweight) of the gelatine-water total. v

This gelatine coating may be dried in heat or in the ordinaryatmosphere; it may, whilst leaving the warm or hot gelatine bath orshortly thereafter, be run through a fine powder, such as talcum powder,French chalk or fiour or the like, so as to render it non-tacky, makingit possible to wind it.

The thread can, if desired, be left partially soluble, leaving, afterdissolving most of the glue and gelatine, a rubber thread structurecapa-' I semi-vulcanised so that the subsequent boiling.

ble after incorporation into fabrics by means of weaving, knitting orlacing and the like, of imparting to such fabrics a certain amount ofelasticity.

It is to be understood that the threads ready for weaving may compriseeither the uncoated or uncovered rubber itself, or may comprise thosewith a winding thereon of silk, cotton, or other fibrous material.

yards to the pound dye right through fairly easily in the cold, butthicker ones will not get dyed right into the core unless Prolongedboiling in dyestufi is given of at least half an hour to one hour.

This is when this thread is still in the unvulcanised condition; whenvulcanised, the thread must be dyed bymeans of a cold process. whenthere is a risk of overvulcanising the thread in the boiling process.

Practically the whole range of known dyestufis may be used. Examples ofsuitable dyes are as follows:

Direct dyes Benzidine and its derivatives Congo red Toluidine Vat dyesIndigo Indanthrene Anthraquinone As regards vulcanisation, in the normalprocedure a boiling out of the setting agent will happen simultaneouslywith dyeing, i. e.,after the set and coated thread has been incorporatedinto fabric, 1. e., in the grey cloth, this grey cloth is then dyed byboiling, causing the thread to be dc-set, to'become flexible, and tobecome vulcanised at the same time. a

To effect vulcanisation a water soluble accelerator of vulcanisationshould be present in the desetting bath such as sodiumdiethyldithiocarbamate, piperidine l-carbothionolate, and the like.

A suitable desetting bath may be made up of a 1 per cent. solution ofsodium diethvldithiocarbamate and a dye such as indigo, and the rubberfabric when boiled in this bath will be deset, and simultaneously dyedand vulcanised.

The vulcanisation takes place chiefly in the dyeing-boiling process whenthe yarn is already in the piece, but in many instances I also vulcanisethe thread after or before the gelatine coating has been applied so thatthe yarn, ready for weaving or knitting, is already vulcanised or in thepiece will either be short and of not sufficient duration to influencevulcanisation or to be so much as to complete the partial vulcanisationalready given to the thread before its incorporation in the fabric.

Instead of being extruded the thread may be formed bya disc method forexample as in my U. 8. Patents Nos. 2,163,986 and Reissue No. 21,090,and in the case of extrusion coagulant may be extruded into latex,and/or the setting agent may be mixed with the coagulant as described inmy U. 8. Patent No. 2,203,701.

In a variation, the thread, when coming from the thread making machineand therefore in a wet condition and tacky, may be coated with asolution of cellulose acetate or similar material, so as to coat thetacky thread with a very thin film of non-tacky material, whereby thethread on arrival at the end of the heating and drying apparatus isabsolutely non-tacky and can therefore be wound as required at oncewithout stretch if so desired either direct on to a weaving pirn or inthe form of a cheese. bobbin or the like.

The application of the cellulosic or like coating renders the threadabsolutely non-tacky and it also prevents the thread from being rapidlyAs regards dyeing, thin threads u to 8000 '16 aflectedby atmosphericmoisture.

Various methods may be adopted for applying such film, for xample:

(a) the thread may be run into a normal coagulant, then passed through adilute. bath of cellulose acetate in acetone (about 5 per cent.strength) and then through a bath of water;

(1)) the thread may be run into a bath containing acetic acid, acetoneand the acetate, dispensing with water and allowing the heat in theheating chamber to dry off the solvents, thus leaving the surface in anon-tacky condition;

the thread however prepared may be run through a normal coagulant passedthrough the acetate solution and then dried by passing it through adrying chamber, or

(d) the thread may be run into the ordinary coagulant to which has beenadded a small quantity of acetate in acetone and then passing the threadthrough water and then drying.

Other materials besides cellulose acetate may be used, for example,substances which can be dissolved in a volatile solvent and which may beeasily separated from such solvent by heat, chemical action or any ofthe known methods, and leaving a non-tacky film.

As examples there may be mentioned cellulose nitrate, viscose (to beprecipitated in dilute acids), cellulose ethers and cellulose esters.

The term latex includes aqueous dispersions of rubber, gutta-percha,balata or similar materials.

I claim:

1. Rubber goods, such as strips, threads, filaments and the'like, havinga coating of an adhesive setting agent, retaining the goods undertension and substantially inelastic, and incorporating an adhesivesetting agent in the body thereof, said agents being capable ofdissolving without injury to said goods for imparting elasticitythereto.

'2. Rubber goods, such as strips, threads, filaments and the like,having an adhering film comprising a setting agent and alsoincorporating a setting agent in the body thereof, said agents renderingthe goods substantially inelastic and being capable or dissolving out inaqueous solution without injury to said goods for imparting elasticitythereto.

3. A tabric, containing woven rubber thread having a coating of anadhesive setting agent and also incorporating said agent in the body 01'said thread, said agent rendering said thread substantially inelasticand being capable of dissolving out without injury to said thread forimparting elasticity to said fabric.

a. A fabric, containing woven rubber thread having a coating of anadhesive setting agent and also incorporating an adhesive setting agentin the body or said thread, said [agents rendering said threadsubstantially inelastic and being capable of dissolving in aqueoussolution without imury to said thread for imparting elasticity tosaidfabric.

5. As a new article of manufacture, a vulcanized rubber thread which isheld in elongated condition .under a predetermined amount of stretch, bya soluble setting agent incorporated in the body thereof and also bysoluble coating material carried thereon, the thread being therebysubstantially deprived of its elasticity but being inherently elasticexcept for said setting agent and coating.

6. A thread comprising a body of rubber composition having a solublesize deposited thereon and also incorporating a setting agent in thebody of the thread, to hold said body in a stretched and substantiallyinelastic condition so that it may be woven or knitted withoutelongating or contracting from this condition to an appreciably greaterdegree than inelastic yarn, the thread being inherently elastic exceptfor said size and setting agent.

material.

THOMAS LEWIS SHEPHERD.

